The present invention relates to an electrically actuatable fuel-injection valve for internal combustion engines. It is suitable for the following proposed valve.
An electrically actuatable fuel-injection valve for internal combustion engines has a piezoelectric hollow cylindrical radial vibrator within the wall of which a plurality of fuel-receiving chambers are arranged parallel and concentric to a longitudinal axis of the radial vibrator, each of which chambers is in communication at one open end with a fuel feed path while at the other open end it has an ejection opening (=outlet opening).
This object is an electrically actuatable fuel-injection valve for internal combustion engines which is characterized by the fact that it has a piezoelectric vibrator with electrodes and at least one fuel-receiving chamber, and that in fuel conducting communication with the chamber there are a fuel feed path and an ejection opening which are so developed that when voltage is applied to the electrodes the fuel is imparted a preferred movement through the chamber to the ejection opening. Specifically, as piezoelectric vibrator there is provided a hollow cylindrical radial vibrator within the wall of which a number of continuous fuel-receiving chambers are arranged parallel and concentric to a longitudinal axis of the radial vibrator.
With the piezoelectric vibrator as well as the fuel feed path which is in communication with it as well as the ejection opening, which at the same time is the outlet opening of the vibrator, the fuel-injection valve is, without any element which is movable as a whole and in particular without a longitudinally displaceable valve needle, to determine the preferred movement of the liquid fuel, namely the direction of injection, and at the same time to feed the measured amount of fuel and create the prerequisite for atomization of the fuel. This is achieved in the manner that upon the application of electrical voltage to electrodes of the piezoelectric vibrator the latter contracts or expands as a result of the electrical field so that the volume of the fuel-receiving chamber changes, that upon a change in volume of the chamber the fuel emerges essentially from the ejection opening while the return flow of fuel through the fuel feed path is substantially throttled.
In general, in order to achieve a substantial mixing of air and fuel it is desirable that the fuel-injection valve produce an atomized fuel jet which is as wide as possible. In known fuel-injection valves it has been attempted to achieve this by various structural measures, the fuel jet, however, being regularly injected in the longitudinal axis of the fuel-injection valve from the valve into the surrounding volume. If the fuel-injection valve is located, as in central injection systems, completely within the stream of air drawn in by the internal combustion engine, said stream of air moves past the outside of the fuel-injection valve and, due to its flow velocity, counteracts the desired widening of the jet of fuel.